Publications by authors named "Melanie Y White"

Article Synopsis
  • Researchers created two types of resins using desferrioxamine B (DFOB), one as a free ligand and the other with its Fe(iii) complex, to identify proteins linked to iron uptake through siderophores.
  • Despite extensive analysis, no proteins associated with Fe(iii) uptake were found, but nickel superoxide dismutase (NiSOD) was discovered to be preferentially bound to the apo-DFOB resin.
  • The study suggests that DFOB can form a complex with NiSOD, indicating that the metal-binding properties of siderophores may affect various biological functions beyond just iron acquisition.
View Article and Find Full Text PDF

The incidence of type 2 diabetes (T2D) is increasing globally, with long-term implications for human health and longevity. Heart disease is the leading cause of death in T2D patients, who display an elevated risk of an acute cardiovascular event and worse outcomes following such an insult. The underlying mechanisms that predispose the diabetic heart to this poor prognosis remain to be defined.

View Article and Find Full Text PDF

Background: Type I interferons (IFN-I) are key responders to central nervous system infection and injury and are also increased in common neurodegenerative diseases. Their effects are primarily mediated via transcriptional regulation of several hundred interferon-regulated genes. In addition, IFN-I activate several kinases including members of the MAPK and PI3K families.

View Article and Find Full Text PDF

Background: Ischemia-reperfusion injury (IRI) is one of the major risk factors implicated in morbidity and mortality associated with cardiovascular disease. During cardiac ischemia, the buildup of acidic metabolites results in decreased intracellular and extracellular pH, which can reach as low as 6.0 to 6.

View Article and Find Full Text PDF

Cysteine (Cys) is a major target for redox post-translational modifications (PTMs) that occur in response to changes in the cellular redox environment. We describe multiplexed, peptide-based enrichment and quantitative mass spectrometry (MS) applied to globally profile reversible redox Cys PTM in rat hearts during ischemia/reperfusion (I/R) in the presence or absence of an aminothiol antioxidant, -2-mercaptopropionylglycine (MPG). Parallel fractionation also allowed identification of irreversibly oxidized Cys peptides (Cys-SOH/SOH).

View Article and Find Full Text PDF

is a major gastrointestinal pathogen generally acquired consumption of poorly prepared poultry. -linked protein glycosylation encoded by the gene cluster targets >80 membrane proteins and is required for both nonsymptomatic chicken colonization and full human virulence. Despite this, the biological functions of -glycosylation remain unknown.

View Article and Find Full Text PDF

Apolipoprotein A-I (apoA-I) is the major component of HDL and central to the ability of HDL to stimulate ATP-binding cassette transporter A1 (ABCA1)-dependent, antiatherogenic export of cholesterol from macrophage foam cells, a key player in the pathology of atherosclerosis. Cell-mediated modifications of apoA-I, such as chlorination, nitration, oxidation, and proteolysis, can impair its antiatherogenic function, although it is unknown whether macrophages themselves contribute to such modifications. To investigate this, human monocyte-derived macrophages (HMDMs) were incubated with human apoA-I under conditions used to induce cholesterol export.

View Article and Find Full Text PDF

While age-related insulin resistance and hyperinsulinemia are usually considered to be secondary to changes in muscle, the liver also plays a key role in whole-body insulin handling and its role in age-related changes in insulin homeostasis is largely unknown. Here, we show that patent pores called 'fenestrations' are essential for insulin transfer across the liver sinusoidal endothelium and that age-related loss of fenestrations causes an impaired insulin clearance and hyperinsulinemia, induces hepatic insulin resistance, impairs hepatic insulin signaling, and deranges glucose homeostasis. To further define the role of fenestrations in hepatic insulin signaling without any of the long-term adaptive responses that occur with aging, we induced acute defenestration using poloxamer 407 (P407), and this replicated many of the age-related changes in hepatic glucose and insulin handling.

View Article and Find Full Text PDF

Myeloperoxidase (MPO) released at sites of inflammation catalyzes the formation of the oxidants hypochlorous acid (HOCl) and hypothiocyanous acid (HOSCN) from H2O2 and halide and pseudo-halide ions. HOCl, a major oxidant produced under physiological conditions reacts rapidly with many biological molecules, and is strongly linked with tissue damage during inflammatory disease. The role of HOSCN in disease is less clear, though it can initiate cellular damage by pathways involving the selective oxidation of thiol-containing proteins.

View Article and Find Full Text PDF

Cysteine (Cys) oxidation is a crucial post-translational modification (PTM) associated with redox signaling and oxidative stress. As Cys is highly reactive to oxidants it forms a range of post-translational modifications, some that are biologically reversible (e.g.

View Article and Find Full Text PDF

Myocardial ischemia and cardioprotection by ischemic pre-conditioning induce signal networks aimed at survival or cell death if the ischemic period is prolonged. These pathways are mediated by protein post-translational modifications that are hypothesized to cross-talk with and regulate each other. Phosphopeptides and lysine-acetylated peptides were quantified in isolated rat hearts subjected to ischemia or ischemic pre-conditioning, with and without splitomicin inhibition of lysine deacetylation.

View Article and Find Full Text PDF

Cardiovascular disease (CVD) in one of the leading causes of mortality and morbidity worldwide, accounting for both primary diseases of the heart and vasculature and arising as a co-morbidity with numerous pathologies, including type 2 diabetes mellitus (T2DM). There has been significant emphasis on the role of the genome in CVD, aiding in the definition of 'at-risk' patients. The extent of disease penetrance however, can be influenced by environmental factors that are not detectable by investigating the genome alone.

View Article and Find Full Text PDF

Inflammatory monocyte-derived effector cells play an important role in the pathogenesis of numerous inflammatory diseases. However, no treatment option exists that is capable of modulating these cells specifically. We show that infused negatively charged, immune-modifying microparticles (IMPs), derived from polystyrene, microdiamonds, or biodegradable poly(lactic-co-glycolic) acid, were taken up by inflammatory monocytes, in an opsonin-independent fashion, via the macrophage receptor with collagenous structure (MARCO).

View Article and Find Full Text PDF

Pseudomonas aeruginosa is the predominant cause of mortality in patients with cystic fibrosis (CF). We examined the secretome of an acute, transmissible CF P. aeruginosa (Australian epidemic strain 1-R; AES-1R) compared with laboratory-adapted PAO1.

View Article and Find Full Text PDF

The more than 300 currently identified post-translational modifications (PTMs) provides great scope for subtle or dramatic alteration of protein structure and function. Furthermore, the rapid and transient nature of many PTMs allows efficient signal transmission in response to internal and environmental stimuli. PTMs are predominantly added by enzymes, and the enzymes responsible (such as kinases) are thus attractive targets for therapeutic interventions.

View Article and Find Full Text PDF

Redox regulation is emerging as an important post-translational modification in cell signaling and pathogenesis. Cysteine (Cys) is the most redox active of the commonly coded amino acids and is thus an important target for redox-based modifications. Reactions that oxidize the Cys sulfur atom to low oxidation states (e.

View Article and Find Full Text PDF

Diagnosis of acute coronary syndromes is based on protein biomarkers, such as the cardiac troponins (cTnI/cTnT) and creatine kinase (CK-MB) that are released into the circulation. Biomarker discovery is focused on identifying very low abundance tissue-derived analytes from within albumin-rich plasma, in which the wide dynamic range of the native protein complement hinders classical proteomic investigations. We employed an ex vivo rabbit model of myocardial ischemia/reperfusion (I/R) injury using Langendorff buffer perfusion.

View Article and Find Full Text PDF

Protein phosphorylation underpins major cellular processes including energy metabolism, signal transduction, excitation-contraction coupling, apoptosis, and cell survival mechanisms and is thus critical to the myocyte. Targeted approaches, whereby a handful of phosphoproteins are investigated, can suffer from a relatively narrow view of cellular phosphorylation. In contrast, recent technical advances have allowed for the comprehensive documentation of phosphorylation events in complex biological environments, providing a deeper view of the "phosphoproteome.

View Article and Find Full Text PDF

Extracellular and cell surface proteins are generally modified with N-linked glycans and glycopeptide enrichment is an attractive tool to analyze these proteins. The role of N-linked glycoproteins in cardiovascular disease, particularly ischemia and reperfusion injury, is poorly understood. Observation of glycopeptides by mass spectrometry is challenging due to the presence of abundant, nonglycosylated analytes, and robust methods for purification are essential.

View Article and Find Full Text PDF

The ability to decipher the dynamic protein component of any system is determined by the inherent limitations of the technologies used, the complexity of the sample, and the existence of an annotated genome. In the absence of an annotated genome, large-scale proteomic investigations can be technically difficult. Yet the functional and biological species differences across animal models can lead to selection of partially or nonannotated organisms over those with an annotated genome.

View Article and Find Full Text PDF

This unit outlines the steps required to prepare a sample for MS analysis following protein separation or enrichment by gel electrophoresis, liquid chromatography, and affinity capture within the context of a bottom-up proteomics workflow in which the protein is first broken up into peptides, either by chemical or enzymatic digestion, prior to MS analysis. Also included are protocols for enrichment at the peptide level, including phosphopeptide enrichment and reversed-phase chromatography for sample purification immediately prior to MS analysis. Finally, there is a discussion regarding the types of MS technologies commonly used to analyze proteomics samples, as well as important parameters that should be considered when analyzing the MS data to ensure stringent and robust protein identifications and characterization.

View Article and Find Full Text PDF

High abundance proteins in serum and plasma (e.g., albumin) are routinely removed during proteomic sample processing as they can mask lower abundance proteins and peptides of biological/clinical interest.

View Article and Find Full Text PDF

Bladder cancer (BLCa) is a severe urological cancer of both men and women that commonly recurs and once invasive, is difficult to treat. MINA-05 (CK Life Sciences Int'l, Hong Kong) is a derivative of complex botanical extracts, shown to reduce cellular proliferation of bladder and prostate carcinomas. We tested the effects of MINA-05 against human BLCa cell sublines, B8, B8-RSP-GCK, B8-RSP-LN and C3, from a transitional cell carcinoma, grade IV, to determine the molecular targets of treatment by observing the cellular protein profile.

View Article and Find Full Text PDF

Cardiovascular disease remains the most common cause of death in the developed world and is predicted by the World Health Organization to kill approximately 20 million people worldwide each year until at least 2015. In light of these figures, work on producing superior tools for clinical use in the cardiovascular field is intensive. As proteins are the primary effectors of cellular function, a significant majority of this work focuses on the role of proteins in the cardiovascular system in physiological and pathological states in order to outline both mechanisms and markers of disease.

View Article and Find Full Text PDF